Features: Secure and Resettable: Smart 4-digit resettable bike chain lock is more secure than other ordinary locks. Easy to set your own personalized number combination. Robust and Durable: It's hard to break through as the lock cylinder of the bike lock is made of zinc alloy. The bicycle chain lock is made of 4mm alloy steel which is drill-resistant and anti-tech unlocking. Easy to Use: Combination locking mechanism provide keyless convenience and set your own password by easy steps. Muti-purpose: Long enough to lock 2-3 bikes together or lock your bike to a tree gate fence railing thick pole and others. After-service: If you have any questions after receiving the product please feel free to contact us and we will provide you with a satisfactory answer. Specification: Material:Aluminum alloy synthetic steel dustproof cloth Length: 85cm Weight: 315g Diameter: 4mm includes: 1 *Bike Lock "